My most recently bottled kombucha was made with brown rice syrup, which contains a lot of non-fermentable solids. It was very cloudy and had a lot of sediment (over an inch in my gallon brew jar). Even ignoring the sediment (which settled), it it was still really cloudy. This prompted me to do a little research on what’s used in the beer and wine world.
Based my research and what I could find, I settled on calcium bentonite powder or gelatin powder. I already have the bentonite powder, but it appears that it requires a bit more time to work. So I picked up a $1.49 bottle of gelatin finings at my local Friar Tuck. I soaked 1 tsp of gelatin with 1/4 cup of distilled water, let it sit for 30 minutes, and then microwaved it for ~30 seconds (until it was clear). I added that to my quart of pomegranate kombucha that was especially cloudy and sedimenty. I think this is supposed to be enough to treat 5 gallons, so I did this knowing that I could end up losing flavor too, but I wasn’t too concerned about that since I didn’t especially care for the flavor. I also used more than called for simply because I was going to be drinking this within 24-48 hours, and it’s not going to have a lot of time to work.
My peach bottle quart was also cloudy, but has a lot less sediment. With it, I was very careful to let things settle before pouring off a little into a “clean” jar. The sediment is very light, and starts to mix whenever the jar is touched, so my second jar was bound to have a lot of sediment remaining. Two days after adding gelatin, my kombucha was clear, bright red, and the sediment had compressed from 4 inches to 2, and I was able to pour out all but 1/4 inch of clear kombucha before the sediment started mixing. The flavor was different, but I’m not sure it was milder. Next time I should clarify it before adding the post-ferment flavoring.
It’s interesting that gelatin or bentonite can be added (to wine) before fermentation begins, so if I end up with something else that tends to produce sediment or cloudiness, I may try adding some at the beginning. Unfortunately, that’s not compatible with continuous brewing, which is the end-goal if I ever settle on a process.